Nuclear Magnetic Resonance (NMR) is a physical characteristic of numerous nuclides which permits their detection and chemical characterization by appropriate instruments. Recently NMR Scanners have been developed which allow in-vivo detection and subsequent spatial localization (imaging) of several biologically important nuclides, particularly 1H and 31P. These techniques will be used to evaluate stroke in animals and human patients. 1H imaging and measurements of spin density, T1 and T2 will be performed in rats with occlusive middle cerebral artery infarcts, gerbils with internal carotid occlusive ischemia, and patients with thromboembolic infarction. In each case, the NMR measurements will be correlated with clinical status, other ancillary techniques such as CT, and histopathology, when available. Ischemic regions in the above animal models will also be investigated with NMR surface coils for measurement of 31P spectra which will be used to evaluate high energy phosphate cellular metabolism. The results from all experiments will be analyzed to determine changes in the early dynamic stages of stroke, parameters useful in the management of stroke, and factors indicative of prognosis.